Study of anatase-rutile transition phase in monolithic catalyst V2O5/TiO2 and V2O5-WO3/TiO2

Using different commercial TiO2 (anatase) powders, monolithic honeycomb str uctures were obtained by cold extrusion. In order to compare the anatase-ru tile transformation for the V-Ti-O system with and without the presence of WO3, two systems were considered: V2O5-WO3/TiO2 and V2O5/TiO2 The FT-IR, XR D analyses and SEM observations show that the presence of WO3 influences bo th the morphology and the rate of formation of the rutile particles. the pr esence of WO3 increases the rate of particle propagation, which becomes hig her than that of the nucleation process; the rutile particles are already e vidently plate-shaped at the beginning of the phase transition. On the cont rary, in titania powders which do not contain WO3, the propagation rate is lower than the nucleation process, the rutile particles have a rod-like sha pe and their presence can be detected by XRD analysis only when the anatase -rutile phase transformation is in progress. (C) 2001 Elsevier Science B.V. All rights reserved.